"Missing Default Layout" pop-up appears when cancelling the "Unsaved Changes Detected" prompts when resetting layout with unsaved UI Builder changes

Steps to reproduce:

1. Create a new 3D URP project
2. Create a new UI Document and open it in UI Builder
3. Make a change so that there are unsaved changes (e.g. add a VisualElement)
4. At the top right of the editor, press on the Layout drop-down then 'Default'
5. In the 'Unsaved Changes Detected' pop-up window, press Cancel on every appeared prompt

Actual results: 'Unsaved Changes Detected' pop-up window appears approximately 4 times and after that 'Missing Default Layout' pop-up window appears offering Quit, Revert Factory Settings, or Cancel

Expected results: 'Unsaved Changes Detected' pop-up window appears only once after pressing Cancel and layout is not changed

Reproducible with versions: 6000.0.43f1, 6000.0.82f1, 6000.3.22f1, 6000.5.8f1, 6000.6.0b9, 6000.7.0a5

Not reproducible with versions: 6000.0.42f1

Tested on (OS): macOS 26.5

Notes:

• On 6.0 the 'Missing Default Layout' pop-up offers only Quit and Revert Factory Settings options, whereas from 6.3+ it offers Quit, Revert Factory Settings, or Cancel